This invention relates generally to aircraft antenna systems and, more particularly, to aircraft antenna systems that conform to the surface of aircraft and electromagnetically excite a least adjacent portions of the aircraft structure. U.S. patent application Ser. No. 08/712,686, filed Sep. 12, 1996 and entitled "Multifunction Structurally Integrated VHF-UHF Aircraft Antenna System," now U.S. Pat. No. 5,825,332 discloses an aircraft antenna system structurally integrated into an aircraft tail fin. Basically, a notch antenna is incorporated into an endcap structure of the vertically oriented tail fin assembly and uses vertically polarized excitation.
Although the prior application referred to above provides good performance of very-high-frequency (VHF) and ultra-high-frequency (UHF) radio signals, there is still a need for an antenna system that produces both vertically polarized and horizontally polarized fields, and that can be integrated into larger load-bearing portions of an aircraft structure rather than a tail fin endcap.
U.S. Pat. No. 5,184,141 to Connolly et al. suggests integration of an antenna into a load-bearing member of an aircraft structure. However, the antenna in Connolly et al. is a dipole or other type of antenna installed behind a transparent window in the aircraft surface, and does not directly excite any portion of the aircraft structure.
Accordingly, there is still a need for a multifunction antenna for installation in manned or unmanned aircraft, with a single radiating element that supports many communication, navigation and identification (CNI) functions, and providing an omnidirectional pattern of both vertically polarized and horizontally polarized radiation. Moreover, the antenna should be of low cost, light weight, and be able to be integrated into larger load-bearing members of the aircraft structure. The present invention meets all these needs and has additional advantages over the prior art.